2.98023e-08 is 0.0000000298023. If you look up the value 2.98023e-08 on Google or another search engine, you can find several examples of people getting that value because of rounding errors. Rounding errors occur because of how computers treat floating-point numbers.

It's probably a rounding error from the interpolation code that colorizeWithColor uses, and you get it instead of zero. For practical purposes, when talking about color components about to be displayed to an end user, I'd say that anything smaller than 1/256 can be considered to be zero.

You can test if two floating point numbers are "about equal" like this (typed on my phone, not really guaranteed to work):